1. Field
One embodiment of the invention relates to a content protection device and a content protection method for protecting content recorded in a memory card.
2. Description of the Related Art
SD Card Association sets SD-Separate Delivery (SD-SD) standards. 4C Entity, LLC sets Content Protection for Recordable Media (CPRM) for SD-SD using the SD-SD standards (Nakano Kazunori and two others, “SDconnect Digital Rights Management System Technology Using SD Memory Card”, Toshiba review, TOSHIBA CORPORATION, Jul. 1, 2008, Vol. 63, No. 7, p. 31 to 34).
The CPRM for SD-SD prepares a user key and a content key, and records the user key and the content key into a protected area and a user data area, respectively. Content is encrypted with the content key, and the encrypted content is recorded into the user data area or an external storage device. The content key is encrypted with the user key, and the user key is encrypted with a media-specific key specific to an SD memory card. Encrypted content and keys can be dealt with separately from each other owing to the CPRM for SD-SD.
Meanwhile, SD memory cards are often used with portable devices, and are sometimes lost together with portable devices. If a lost portable device is picked up by a third person, there is a risk that the third person may illegally use a content key recorded in the SD card to see content in the SD memory card. Hence, there has been demands for supply of a mechanism which protects contents.